1. Field of the Invention
The invention relates to an ultrasound therapeutic apparatus which irradiates a diseased part of a patient with focused ultrasound beam for therapy thereof.
2. Description of the Related Art
In recent years, attention has been paid to minimally invasive treatment (MIT) a part of which is performed by ultrasonic therapeutic apparatus. Ultrasonic (Ultrasound) therapeutic apparatuses include shock wave lighotriptor which break a calculus with a focused ultrasonic beam and thermotherapy apparatuses which heat and necrotize a diseased part, such as a cancer, with focused ultrasonic beam.
A typical example of a strong ultrasound generating device is a piezoelectric type of device. This type of ultrasound generating device has great advantages that the focus of ultrasonic waves can be localized, few expendable parts are involved, intensity control is easy, the position of the focus can be changed easily by phase control (delay control) of drive voltages to a plurality of piezoelectric transducer elements, etc. (refer to Japanese Unexamined Patent Publication No. 60-145131 and U.S. Pat. No. 4,526,168).
The MIT is also a key word in the field of cancer therapy. Under the present conditions, most of cancer therapies rely on surgical operations. Thus, the outward form and the inherent function of an organ having cancer are destroyed very frequently. In such a case, so much strain will be put on a patient even if he or she lives long after operation. From a viewpoint of quality of life (QOL), therefore, the development of a new therapy (equipment) that is little invasive is being desired.
Under such circumstances, as one of therapies for malignant tumors, or cancers, the therapy by hyperthermia has drawn attention, which, using a difference in sensitivity to heat between tumor tissues and normal tissues, selectively destroys only cancer cells by heating a diseased part to 42.5xc2x0 C. or more for a long period of time. As a method of application of heat to the body, a method of using electromagnetic waves such as microwaves has preceded. With this method, however, the electrical characteristics of a living body make it difficult to selectively heating a tumor in the deep of the body. Satisfactory results cannot therefore be expected for tumors existing 5 cm or more deep in the body. For this reason, a method of utilizing ultrasonic energy has been proposed for therapy for tumors existing in the deep of the body (refer to Japanese Unexamined Patent Publication No. 61-13955).
The ultrasound-based thermotherapy has been developed into a therapy which, by sharply focusing ultrasonic waves generated by piezoelectric transducer elements onto a diseased part, heats a tumor to 80xc2x0 C. or more and necrotizes tumor tissues in an instant (refer to U.S. Pat. No. 5,150,711). In this therapy, unlike the conventional hyperthermia, it is a very important subject to precisely match the focus or point of application of focused ultrasonic waves with a diseased part in order to introduce ultrasonic waves at a very great intensity (some hundreds to some thousands of W/cm2) into a restricted region in the vicinity of the focus of the ultrasonic waves and necrotize the diseased part instantly.
Methods of solving that problem are disclosed in Japanese Unexamined Patent Publications Nos. 61-13954, 61-13956, and 60-145131. According to these methods, the spatial intensity distribution of therapeutic ultrasonic waves is obtained by first detecting by an imaging probe echoes from the focus region of the waves pulses emitted from a therapeutic ultrasonic source, and then performing a B-mode process on the received echo signal.
However, these methods have the following problem. Whereas the frequency of the therapeutic ultrasonic waves is in the range of 1 to 3 MHz, the frequency of in vivo imaging ultrasonic waves is 3.5 MHz or more. The resonant frequency of imaging transducer elements coincides with the frequency of the imaging ultrasonic waves. Thus, the imaging probe will receive echoes of therapeutic ultrasonic waves with a very low sensitivity, failing to obtain the intensity distribution with precision.
According to one of these methods, an imaging probe receives echoes of imaging ultrasonic waves generated by that probe and echoes of ultrasonic pulses at the same time. The received signal having two components mixed in is then processed. Thus, this method has a problem that each image contrast cannot be adjusted individually.
According to another of these methods, imaging ultrasonic waves and ultrasonic pulses for intensity distribution are transmitted/received alternately. This approach has an advantage that each image contrast can be adjusted individually, but has a disadvantage that the frame rate is low, making it difficult to accomplish real-time processing.
Moreover, the above methods have the following problem. In general, in cautery treatment based on focusing of high-intensity ultrasonic waves, the location of a region onto which ultrasonic waves are focused and the location of a region to be treated do not match due to changes in acoustic characteristic of a cauterized region. Thus, even if the focus is matched to the part to be treated, the therapy will result in imperfection. Moreover, an adverse effect will also be produced on normal parts.
Furthermore, the above methods have the following problem. Ultrasonic pulses generated from a source of therapeutic ultrasonic waves are reflected from a region in the vicinity of the focus and the resulting echoes are received by an imaging probe. Likewise, imaging ultrasonic waves generated from the imaging probe are reflected from a region in the vicinity of the focus and the resulting echoes are received by the imaging probe. In order to cause a match to occur between the location of the focus on an intensity distribution image and the location of the focus on a B-mode tomographic image, the therapeutic ultrasonic waves and the imaging ultrasonic waves are generated at different times so that the resulting echoes corresponding to both types of waves from the focus will arrive at the probe at the same time. However, the timing of receiving of each echo from the same location other than the focus differs because of differences in propagation path. Thus, a spatial mismatch occurs between an intensity distribution image and a B-mode tomographic image.
It is an object of the invention to provide an ultrasonic therapeutic apparatus which permits the focus of ultrasonic waves to be matched to a treating region with high precision.
According to the present invention is provided an apparatus an ultrasonic therapeutic apparatus comprising:
a therapeutic ultrasonic wave generating source having resonant characteristics for a first fundamental frequency;
an ultrasonic probe having resonant characteristics for the first fundamental frequency and a second fundamental frequency;
driving means for driving the therapeutic ultrasonic wave generating source with a drive signal of the first fundamental frequency;
driving means for driving the ultrasonic probe with a drive signal of the second fundamental frequency to generate in vivo imaging ultrasonic waves;
receiving means for receiving echoes of first ultrasonic waves generated by the therapeutic ultrasonic wave generating source and echoes of second ultrasonic waves generated by the ultrasonic probe through the ultrasonic probe; and
forming means for forming at least an intensity distribution image of the therapeutic ultrasonic waves in a subject or a tomographic image of the subject on the basis of a received echo signal output from the receiving means.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a therapeutic ultrasonic wave generating source having resonant characteristics for first and second fundamental frequencies;
an ultrasonic probe having resonant characteristics for the second fundamental frequency;
driving means for driving the therapeutic ultrasonic wave generating source with a drive signal of the first fundamental frequency at therapy time and with a drive signal of the second fundamental frequency at intensity distribution imaging time;
driving means for driving the ultrasonic probe with a drive signal of the second fundamental frequency to generate in vivo imaging ultrasonic waves;
receiving means for, at intensity distribution imaging time, receiving echoes of the therapeutic ultrasonic waves having a spectrum centered at the second fundamental frequency and echoes of the imaging ultrasonic waves having a spectrum centered at the second fundamental frequency; and
forming means for forming at least an intensity distribution image of the therapeutic ultrasonic waves in a subject or a tomographic image of the subject on the basis of a received echo signal output from the receiving means.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a therapeutic ultrasonic wave generating source having resonant characteristics for a first fundamental frequency;
an ultrasonic probe having resonant characteristics for a second fundamental frequency;
driving means for driving the therapeutic ultrasonic wave generating source with a drive signal of the first fundamental frequency;
driving means for driving the ultrasonic probe with a drive signal of the second fundamental frequency to generate in vivo imaging ultrasonic waves;
receiving means for receiving echoes of first ultrasonic waves generated by the therapeutic ultrasonic wave generating source and echoes of second ultrasonic waves generated by the ultrasonic probe through the ultrasonic probe;
intensity distribution forming means for forming the intensity distribution image of the therapeutic ultrasonic waves in a subject on the basis of components in a specific band corresponding to the first fundamental frequency that are contained in a received echo signal from the receiving means; and
forming means for forming a tomographic image of the subject on the basis of components in a band having the second fundamental frequency that are contained in the received echo signal output from the receiving means.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
driving means for driving the source to generate first ultrasonic waves; and
adjust means for adjusting drive conditions of the driving means on the basis of echoes of the first ultrasonic waves received through the ultrasonic probe.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
first driving means for driving the source to generate first ultrasonic waves;
second driving means for driving the ultrasonic probe to generate imaging ultrasonic waves;
means for forming the intensity distribution of the first ultrasonic waves and a tomographic image of a subject on the basis of echoes of the first ultrasonic waves and echoes of the imaging ultrasonic waves received through the ultrasonic probe; and
determination means for determining the presence or absence of an obstruction to ultrasonic waves on the basis of the shape of the intensity distribution.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
means for driving the source to generate therapeutic ultrasonic waves;
means for driving the ultrasonic probe to generate imaging ultrasonic pulses;
receiving means for receiving echoes through the ultrasonic probe;
means for forming a tomographic image of a subject on the basis of the echoes received; and
means for adjusting the timing of the therapeutic ultrasonic waves so that noise resulting from the therapeutic ultrasonic waves being stronger than the imaging ultrasonic pulses will appear in other portions of the tomographic image than a portion of interest.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
driving means for driving the source to generate therapeutic ultrasonic waves;
a magnetic resonance diagnostic apparatus for measuring the temperature distribution in the vicinity of the focus onto which the therapeutic ultrasonic waves converge; and
means for adjusting drive conditions of the drive means according to the temperature distribution.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
driving means for driving the source to generate first ultrasonic waves;
forming means for forming intensity distribution of the first ultrasonic waves on the basis of echoes of the first ultrasonic waves received through the ultrasonic probe;
magnetic resonance diagnostic means for measuring one-dimensional temperature distribution; and
estimation means for estimating two-dimensional temperature distribution on the basis of the intensity distribution and the one-dimensional temperature distribution.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
sync signal generating means for generating first and second sync signals;
driving means for driving the source of therapeutic ultrasonic waves according to the first sync signal;
driving means for driving the ultrasonic probe according to the second sync signal;
phase shift means for changing the difference of the first sync signal in time relative to the second sync signal to impart phase differences to echoes of first ultrasonic wave generated by the therapeutic ultrasonic wave generating means. receiving means for receiving echoes of the first ultrasonic waves and echoes of second ultrasonic waves generated by the ultrasonic probe through the ultrasonic probe; and
forming means for forming an image on the basis of received signals output repeatedly from the receive means, the received signals being phase-shifted by the phase shift means.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
means for driving the source of therapeutic ultrasonic waves;
means for driving the ultrasonic probe to generate imaging ultrasonic waves;
receiving means for receiving echoes of first ultrasonic waves generated by the therapeutic ultrasonic wave generating source and echoes of second ultrasonic waves generated by the ultrasonic probe through the ultrasonic probe;
first filtering means for extracting a first component within a first specific band corresponding to the fundamental frequency of the first ultrasonic waves from an output of the receiving means;
second filtering means for extracting a second component within a specific band corresponding to the fundamental frequency of the second ultrasonic waves from the output of the receiving means;
means for amplifying each of the first and second components individually; and
means for forming an image on the basis of the first and second components amplified by the amplifying means.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a therapeutic ultrasonic wave generating source having first resonant characteristics for a first frequency;
an ultrasonic probe having second resonant characteristics for a second frequency;
means for applying to the therapeutic ultrasonic wave generating source a drive signal of a frequency between the first and second frequencies;
means for driving the ultrasonic probe to generate imaging ultrasonic waves;
receiving means for receiving echoes of ultrasonic waves from emitted the therapeutic ultrasonic wave generating source and echoes of the imaging ultrasonic ultrasonic waves through the ultrasonic probe; and
means for constructing an image on the basis of an output of the receiving means.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
first drive means for driving the source of therapeutic ultrasonic waves;
second drive means for driving the ultrasonic probe to generate in vivo imaging ultrasonic waves;
constructing means for constructing the intensity distribution of the therapeutic ultrasonic waves and a tomographic image of a subject on the basis of echoes of first ultrasonic waves from the source and echoes of second ultrasonic waves from the ultrasonic probe received through the ultrasonic probe; and
means for estimating a treating region which is heated to a predetermined temperature or more on the basis of the intensity distribution.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
drive means for driving the source of therapeutic ultrasonic waves to generate ultrasonic waves that converge onto a focus;
drive means for driving the ultrasonic probe to generate in vivo imaging ultrasonic waves;
constructing means for constructing the intensity distribution of the ultrasonic waves and a tomographic image of a subject on the basis of echoes of the ultrasonic waves from the source and echoes of the imaging ultrasonic waves from the ultrasonic probe received through the ultrasonic probe; and
means for detecting a focal region of therapeutic ultrasonic waves on the basis of the intensity distribution;
means for forming the focus of therapeutic ultrasonic waves in a first focal position and a second focal position; and
means for displaying a combined region of a first focal region corresponding to the first focal position and a second focal region corresponding to the second focal position on the tomographic image.
According to the present invention is provided an apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
drive means for driving the source of therapeutic ultrasonic waves to generate first ultrasonic waves;
drive means for driving the ultrasonic probe to generate second ultrasonic waves for in vivo imaging;
constructing means for constructing the intensity distribution of the first ultrasonic waves and a tomographic image of a subject on the basis of echoes of the first ultrasonic waves from the source and echoes of the second ultrasonic waves from the ultrasonic probe received through the ultrasonic probe; and
means for correcting spatial displacement of the intensity distribution with respect to the tomographic image on the basis of differences among propagation paths of ultrasonic waves.
According to the present invention is provided an other apparatus an ultrasonic therapeutic apparatus comprising:
a source of therapeutic ultrasonic waves;
an ultrasonic probe;
drive means for driving the source of therapeutic ultrasonic waves to generate first ultrasonic waves;
drive means for driving the ultrasonic probe to generate second ultrasonic waves for in vivo imaging;
constructing means for constructing the intensity distribution of the first ultrasonic waves and a tomographic image of a subject on the basis of echoes of the first ultrasonic waves from the source and echoes of the second ultrasonic waves from the ultrasonic probe received through the ultrasonic probe; and
means for adjusting the timing of the first ultrasonic waves relative to the second ultrasonic waves to correct spatial displacement of the intensity distribution with respect to the tomographic image on the basis of differences among propagation paths of ultrasonic waves.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.